[Feature:TAGrading] websockets for checkpoint & numeric

[marwanatef2]

Please check if the PR fulfills these requirements:

• The PR title and message follows our guidelines
• Tests for the changes have been added/updated (if possible)

What is the current behavior?

Simple grading (checkpoints / numeric) is accessed by multiple graders simultaneously but doesn't refresh upon changes so graders can't see the latest page updates.

What is the new behavior?

Integrating websockets in simple grading will allow changes to any checkpoint/numeric-input to take place concurrently on all open graders pages (windows) so they can see the latest updates in real time.

[codecov]

Codecov Report

Merging #5829 into master will decrease coverage by 1.97%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #5829      +/-   ##
============================================
- Coverage     22.53%   20.55%   -1.98%     
- Complexity     6199     6914     +715     
============================================
  Files           157      157              
  Lines         20281    22384    +2103     
============================================
+ Hits           4570     4602      +32     
- Misses        15711    17782    +2071     

Flag	Coverage Δ	Complexity Δ
#autograder	9.72% <ø> (ø)	0.00 <ø> (ø)
#migrator	99.10% <ø> (ø)	0.00 <ø> (ø)
#php	19.48% <ø> (-2.09%)	6914.00 <ø> (+715.00)	⬇️
#python_submitty_utils	82.32% <ø> (ø)	0.00 <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

[jchulton]

Tested and working, just the question above.